Repositório Comunidade:http://hdl.handle.net/10362/35852016-12-09T15:28:57Z2016-12-09T15:28:57ZBiogenic amines in wine: gene transcription as a tool for selection of Oenococcus oeni starter strainsMarques, Ana Paula Gomeshttp://hdl.handle.net/10362/85542015-10-03T03:40:40Z2012-01-01T00:00:00ZTítulo: Biogenic amines in wine: gene transcription as a tool for selection of Oenococcus oeni starter strains
Autor: Marques, Ana Paula Gomes
Resumo: Wine is a complex environment where the microbial flora can have both a
positive (e.g. malolactic fermentation) and a negative (e.g. production of
biogenic amines) impact on the quality of wine.
Biogenic amines are nitrogenous compounds of low molecular weight that can
be found in fermented food and beverages, including wine. Biogenic amines
are formed primarily by decarboxylation of the corresponding amino acids by
microorganisms through substrate-specific decarboxylases. Some authors
consider the presence of biogenic amines to be a fundamental parameter for
detriment of alcoholic beverages. These compounds can have adverse health
effects on sensitive individuals at high concentrations.
The role of microorganisms in wine involves two important fermentation
processes, the alcoholic fermentation conducted by yeasts and the malolactic
fermentation conducted by lactic acid bacteria. The malolactic fermentation
refers to the conversion of L-malic acid into L-lactic acid and CO2, catalysed
by the malolactic enzyme. This mechanism contributes for deacidification,
bacterial stability and flavour changes in wine. Oenococcus oeni is the leading
lactic acid bacteria responsible for malolactic fermentation, mainly due to its
adaptability to such a chemically harsh wine environmental (low pH and high
ethanol concentrations).
The two main goals of this PhD thesis were to contribute to the: (1) increase of
knowledge of biogenic amines occurrence in wine; (2) oenological
characterization and selection of Portuguese autochthonous O. oeni strains,
isolated from different winemaking regions, to be used as malolactic starters
on the wine industry.(...)
Descrição: Dissertation presented to obtain the Ph.D degree in Biology2012-01-01T00:00:00ZDynamics of cork mycobiota throughout stopper manufacturing process: from diversity to metaboliteBarreto, Maria do Carmohttp://hdl.handle.net/10362/68602016-07-25T17:10:51Z2011-12-01T00:00:00ZTítulo: Dynamics of cork mycobiota throughout stopper manufacturing process: from diversity to metabolite
Autor: Barreto, Maria do Carmo
Resumo: Cork, the continuous layer of outer bark of the Quercus suber L.
tree, has physical and chemical properties that are unique.
Portugal possesses 33 % of the world’s cork oak forests and
accounts for approximately half of total global cork production.
The manufacture of cork discs (or stoppers) comprises several
stages, including two boiling stages, during which slabs of cork
are steeped in boiling water. In days following the boiling the
humidity of the slabs decreases and they become completely
covered in a white mycelium of Chrysonilia sitophila until the cork
achieves a certain water activity level (ca 0.9 aw). Below this
level other fungal species (e.g. Penicillium, Aspergillus or
Trichoderma) can germinate and shift the fungal colonization of
the cork slabs.
The two main objectives of the research described in the
presented PhD thesis are (1) a taxonomic identification of the
mycobiota present in cork slabs throughout the manufacture of
cork discs, and (2) an investigation into the chemical compounds,
which can give unfavourable properties to the cork, produced by these fungi.(...)
Descrição: Dissertation presented to obtain the Ph.D degree in Biology2011-12-01T00:00:00ZPenicillium glabrum cork colonising isolates – preliminary analysis of their
genomic similariBasílio, MCGaspar, RSilva, Pereira CSan, Romão MVhttp://hdl.handle.net/10362/37552014-05-30T01:06:07Z2006-01-01T00:00:00ZTítulo: Penicillium glabrum cork colonising isolates – preliminary analysis of their
genomic similari
Autor: Basílio, MC; Gaspar, R; Silva, Pereira C; San, Romão MV
Resumo: Cork stopper manufacturing process includes an operation, known as
stabilisation, by which humid cork slabs are extensively colonised by fungi. The
effects of fungal growth on cork are yet to be completely understood and are
considered to be involved in the so called “cork taint” of bottled wine. It is
essential to identify environmental constraints which define the appearance of
the colonising fungal species and to trace their origin to the forest and/or as
residents in the manufacturing space. The present article correlates two sets of
data, from consecutive years and the same season, of systematic biologic
sampling of two manufacturing units, located in the North and South of Portugal.
Chrysonilia sitophila dominance was identified, followed by a high diversity of
Penicillium species. Penicillium glabrum, found in all samples, was the most
frequent isolated species. P. glabrum intra-species variability was investigated
using DNA fingerprinting techniques revealing highly discriminative polymorphic
markers in the genome. Cluster analysis of P. glabrum data was discussed in
relation to the geographical location of strains, and results suggest that P.
glabrum arise from predominantly the manufacturing space, although cork resident
fungi can also contrib2006-01-01T00:00:00ZScreening pentachlorophenol degradation ability by environmental fungal strains
belonging to the phyla Ascomycota and ZygomycotaCarvalho, M. B.Martins, I.Leitão, M. C.Garcia, H.Rodrigues, C.San Romão, M. VitóriaMcLellan, I.Hursthouse, A.Pereira, Cristina Silvahttp://hdl.handle.net/10362/37542015-10-03T03:41:17Z2010-01-01T00:00:00ZTítulo: Screening pentachlorophenol degradation ability by environmental fungal strains
belonging to the phyla Ascomycota and Zygomycota
Autor: Carvalho, M. B.; Martins, I.; Leitão, M. C.; Garcia, H.; Rodrigues, C.; San Romão, M. Vitória; McLellan, I.; Hursthouse, A.; Pereira, Cristina Silva
Resumo: Pentachlorophenol (PCP) bioremediation by the fungal strains amongst the cork-
colonising community has not yet been analysed. In this paper, the co- and
direct metabolism of PCP by each of the 17 fungal species selected from this
community were studied. Using hierarchical data analysis, the isolates were
ranked by their PCP bioremediation potential. Fifteen isolates were able to
degrade PCP under co-metabolic conditions, and surprisingly Chrysonilia
sitophila, Trichoderma longibrachiatum, Mucor plumbeus, Penicillium janczewskii
and P. glandicola were able to directly metabolise PCP, leading to its complete
depletion from media. PCP degradation intermediates are preliminarily discussed.
Data emphasise the signiWcance of these fungi to have an interesting potential
to be used in PCP bioremediation processes.2010-01-01T00:00:00Z